Telephone system



Oct. '14, 1941. R. c. DAVIS ETAL 2,259,101

TELEPHONE SYSTEM Filed May 15, 1940 11` sheets-sheet 1 Get. 14, 1941.AR. c. Dvis ErAl.

TELEPHON E S YS TEM 11 sheets-shet 2 Filed May l5, 1940 /Nl/,ENTORSATTO/MEV R. c. DAvls ET AL 2,259,101

TELEPHONE SYSTEM Oct. 14, 1941.

Filed May 15, 1940 11 sheets-sheet s R. C. DAV/5 /Nl/E/VTORS J. B.NEWSOM W 8. STR/CKLER By @4M A T rom/5V Oct. 14, 1941. R, Q DAV|$ ETAL2,259,101

TELEPHONE SYS TEM Filed May 15, 1940 l11 sheets-sheet 4 RC. DAV/S/Nl/E'NTORS J.B. NEWSOM 5KB. STR/CKLER Byaeesm A TToRA/Eg Oct. 14, 1941.R. c. DAvls ET AL TELEPHONE SYSTEM Filed May l5, 1940 11 Sheets-Sheet 5www.

k. c. 0A ws /NVENTORS J. a. fvswsou By nf s Tmc/(LER A from/FV Oct. 14,1941. R. c. DAVIS ET AL 2,259,101

TELEPHONE SYSTEM v Filed May 15, 1940 l 11 sheets-sheet s Crm-"1.

RC. DAV /Nl/EA/TORS J. B. NEWSOM W B. STR/CK/.ER

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A T TOR/VE V 0d. 14, 1941. R. c. DAVIS ET Al. 2,259,101

TELEPHONE SYSTEM Filed May 15, 1940 1l Sheets-sheet yr 1 l i I l I l l lI I u l 4 I l l v l FJ m f R. c. 0A ws Qj /NVE/VTORS J. E. NEWSOM t Byma. STR/clam A T TOR/VFY Oct. 14, 1941. R. c. DAvls ET Al.

TELEPHONE SYSTEM ll Sheets-Sheet 9 Filed May 1,5, 1940 R. C. DAV/S /N VEN TORS J. B. NEWSOM By W B. STR/CKLER 606. M

A TTOR/VEV Oct. 14, 1941.

R. c. DAvls ET'AL 2,259,101

TELEPHONE SYSTEM Filed May l5, 1940 11 sheets-sheet 10 l?. DAV/S/NI/ENTORS J. B. NEWSOM n. B. S TR/CKLE'R @y @6. ad

A T TOR/VE V TELEPHONE SYSTEM Filed May l5, 1940 11 Sheets-Sheet l1MARG/N.

MARS/NHL.

A T mlm/EV case gives the identity of the office.

Patented Oct. 14, 1941 TELEPHONE SYSTEM Richard C. Davis and James B.Newsom, Great Neck, N. Y., and Walter B. Strickler, .East Orange, N. J.,assignorsto Bell .Telephone Laboratories, Incorporated, New York, N. Y.,a corporation of New York Application May 15, 1940, Serial No. 335,240

11 Claims.

'This invention relates to telephone systems and has for its object tofacilitate the handling of calls requiring the services of an operator.

In general, it has been found desirable where only a few operators areneeded at individual oiiices to pla-ce these operators at a centralizedpoint where they rnay'serve a number of such oices. Heretofore, vinorder to do this it has been necessary to carry the talking circuitthrough the centralized office thereby introducing sources of trouble.

In accordance with the present invention the talking circuits are freedof these sources of difficulty since instead 1of carrying the talkingcircuits through the centralized oice, the functions vof thevregistering `equipment or senders have been divided into two parts, one.performed at the switching omce and the other performed at theA:centralized oflice, the two parts of the sender being permanently.connected by a lset of four conductors.

In .accordance with `the .present invention where the incoming trunks orjunctors have access to more than one office, means is provided toinform the calling .operator .that the office designation is required.The B operator is also pro- ,vided with means for indicating to thesender to which of the offices the call is directed and the 'sender isprovided with means for combining these indications into an .officeindication to the marker.

.More specifically., during the connection of the 4incoming junctorandthe terminating sender, a group circuit in the link controlcircuitsets up an indication `in the terminating sender which showswhether the calling junctor has access to one or more than one oiice andin the former If the junctor serves a plurality of ofces, theterminating sender passes this information to the centralized Isenderwhich, in turn, modifies the operation of the tone generation yat theoperators position to inform the originating operator that the oilceidentity should be given. The B operator Vreceiving this informationgives a discriminating indication to the centralized sender which4passes this 'information to the terminating sender by to makeselections in the proper ofce.

If lthe sender vdoes not receive a complete desvignation it transmitsaspecial reorder designation to the marker "to cause the transmission ofa reorder Vsignal yto the originating operator.

These and other features of the invention will be -more apparent from alconsideration of the following description in connection 'with lthedrawings in'which:

Fig. 1 shows 'in diagrammatic form 'an originating office, a plurality`of incoming junctors, terminating switches and a plurality of calledlines. In addition, 'it shows apart of the sender link;

Figs. 2, 3, 4, 5 vand '-Z Vshow Apar-ts of ,the sender at the.terminating oiiice, Figs. 2 and 5 showing the connection controlrelays, Fig. 3 showing the pulsing and counting relays, and Figs. 4 and7 showing a cross-bar type :register:

Fig. 6 shows the-operators position at the vcentralized cnice;

Fig. 8 shows fa `part :of the marker;

Figs. 9, 10 and '11:show the recorder and position :finder circuitlocated at the centralized .ofce, Fig. 9 showing .the position iinder,Fig. 10 showing the steering relays and the .counting relays, Fg. 11showing the register relays; and

Fig. 12 shows the manner in which Figs. 1 to 1-1 should be arranged.

For Ia com-plete showing Yof the terminating marker, reference fislhereby made to Patent No. `2,232,371,--granted to J. W. Dehn et al.,Feb. 18, 1941, while vfor a more complete discussion of the trunkng:arrangement .serving a plurality .of .offices `reference is Amade .tothe .application .of Hersey et al., Serial No. 335,241, filed May 15,1940.

Briefly Ythe oper-ation of the present circuit is :as follows: When .acall :originates at a manual junctor.

operators .position 1in the .originating oice |100, the subscriber givesthe wanted number 'to the A operator at lthat oiiice. :The A operatorthen selects an .idle one of .the incoming junctors IUI to |82 .leadingvto `the wanted office and inserts the plug .of .her -cord 4in the jackleading .to that The selection of the jnnctor causes lthe senderVconnector 21H1 :to test for and :connect with the terminating end rof.an idle B sender hereinafter to @be .called the terminating sender.When .the terminating Asender has .been seized it establishes a talkingconnection through lto the centralized end ofthe sender which will vbeknown as the centralized sender. fIlie position nder Ythen hunts for andseizes an idle B .operators position. A tonesignal is thentnansmittedfrom the B position to the A position and the .A operatorrepeats the :wanted ynumber to the B .op-

erator. The .B operator 'then .sets up the number on her key-set 640controlling thereby the registers |IIO, H20, H30 and H00 of Fig. 11.When the registration has been completed the B operators position isreleased and the number is transmitted by means of revertive pulses tothe terminating sender where it is recorded on the cross-bar register ofFigs. 4 and 7. The number is then transferred to the terminating markerof Fig. 8 which selects the wanted line, sets up and tests a connectionbetween the incoming junctor and the Wanted line and then releases thesender which will, in turn, release the marker.

In the present disclosure it has been assumed that incoming junctors I|and |02 from originating office |00 have access to the incoming and lineswitches shown at |06 and through them to lines |01 and |00 in office A.Incoming junctors |03 and |04 represent a group of incoming junctorsfrom an originating cnice |50'which lhas access both to the lines ofvoiice A and to lines of oice B which are not shown. Incoming junctorsare arranged in groups and are connected with senders by means of thesender link H0. In the link control circuit each junctor of a groupoperates a group start relay such as relay H2 or H9 which brings aboutthe connection of the link circuit to the group of junctors by the grouprelay H3 or |20 and the selection of a group of senders including anidle sender by the sender group relay such as relay H4. When these con--nections have been established an indication of the ofce at which thejunctor terminates is prepared by the grounding of one of the conductorsII 5, H 6 or H1. This indication becomes effecl tive when the individualjunctor and sender have Abeen connected. According to thecross-connection as shown, the grounding of conductor H1 indicates ajunctor terminating in oice A, the

-grounding of conductor H6 indicates a junctor `terminating in oiice B,while the grounding of conductor H indicates a junctor having access toeither ofiice A or ofce B.

Call to ojce A Assume that the A operator at the originating 4office inthe extension or" a call to a subscriber at oice A has selected theincoming junctor |0I. This junctor operates groupstart relay I I2 whichin turn brings about the operation of junctor group relay H3 and sendergroup relay H4 and the operation of the switches of the link H0. RelayH3 grounds conductor H1 which is extended by the operation of sendergrouprelay H4, to conductor H8 leading to the sender.

When the switches of link H0 are ready for `operation the link controlcircuit connects ground to conductor III operating relay 500 in theselected sender. Relay 500 extends its operating ground over its innerupper front contact, conductor 56|, inner upper back contact of relay200, conductor to the winding of relay 502 and battery. With relays 500and 502 operated, a number of registrations are made in the sender.Relay 500 also prepares a number of other circuits over which the linkcontrol circuit prepares and tests the connection between the sender andthe incoming junctor.

The identity of the oilice which is served by the incoming junctor IIIIis recorded by the extension of conductor H8 over the outer upper frontcontact of relay 500 to the winding of re- I lay 208 and battery.

The identity of the frame on which the in- -coming junctor is located isrecorded by grounding one of conductors 506 or 501 and one of the upperten conductors leading to armatures of relay 502. Assuming that theframe on which the incoming junctor |0I is located is frame I4,conductors 505 and 503 will be grounded. In addition, since the frame isan even-numbered frame, ground will be connected to conductor 5 I 2leading to the lowest armature of relay 502. The grounding of conductor506 completes a circuit over the third upper front contact of relay 500,conductor 500, through cable 505 to the winding of relay 30| andbattery. Relay 30| extends its operating ground to conductor 302,operating relay 509.

The grounding of conductor 503 completes a circuit over the inner upperfront contact of relay 502, conductor 504, through the cable 505 to thewinding of select magnet 104, Winding of relay and battery. Relay 190 ismarginal and does not operate unless, due to some difficulty, an attemptis made to operate more than one select magnet. Magnet 104 extends itsoperating ground over conductor 10| to the winding of relay 300 andbattery. Relay 300 operates and extends ground from conductor 302, overits outer upper front contact to the normal contacts and Winding ofrelay 202, resistance 203 and battery. Relay 202 operates, lockingdirectly to conductor `302, and preparing a circuit for relay 204 frombattery through resistance 205, winding of relay 200, front contact ofrelay 202 to conductor 302. However, relay 202 does not operate, beingshunted by the operating circuit for relay 202 which extends over theupper back contact of relay 204 to resistance 205.

The grounding of conductor 5I2 completes a circuit over the lowermostfront contact of relay 562 to the winding of relay 5|3 and battery.Relay 5|3 reverses the direction of current flow over the contacts ofstepping relay 5M. Wear on the contact of relay 5I4 is reduced by havingthe current ow reversed for approximately half of the calls. This isaccomplished by carrying the `stepping circuit over the contacts ofrelay 5|3 and operating that relay only for calls over junctorsappearing on even-numbered frames.

When relays 500 and 502 having been operated,

rthe link control circuit tests the holding circuit between the senderand the link switches by operating the switches over a circuit includingconductor 5| I, second lower front contact of relay 500, and conductor201. If this circuit is complete, the control circuit then groundsconductor 5I0, completing a circuit which tests whether the frame tensregistration has been made, extending over the inner lower front contactof relay 500, front contact of relay 509, which was operated by theframe tens relay, lower winding of relay 206 to battery. Relay 206 atits third lower front contact connects ground to conductor 302 toprovide a holding circuit for relays 30|, 202, etc. Relay 206 at itsinner upper front contact connects ground to conductor 2I8, marking thesender busy to the link control circuit.

In response to this ground the link control circuit tests, to determineif one and only one frame registration has been made and if an officeregistration has been made, by connecting ground to conductor 2 I0. Thegrounding of conductor 2I0 completes a circuit over the second lowerfront contact of relay 206, outer upper front contact of relay 208,outer upper back contact of relays 2H and 2I2, outer upper front contactof relay 202, conductor 102, back contact of relay 190, conductor 303,back contact of frame tens relay 304, conductor 209 through cable 505,`to- `the winding of relay 200 and battery. Relay 200 locks over its.inner lower `front contact and conductor 2| 9 to ground at the thirdupper front 'contact of relay 206 and provides a locking cir- ,cuit forrelay 206 which extends from battery on 'conductor 2|3 over itsoutermost lower contact'to conductor 201 to provide a holding circuitfor the link switches and extends the same ground over its fourth loweriront contact and the rthird lower front contact of relay 500 toconductor 5I8 as a release signal to the link control circuit. The linkcontrol circuit responds to ground on conductor 518 by opening thecircuit of relay 500 which now releases.

The sender now remains connected with Athe y junctor by means ofconductors 2|4 to 2I1 and '5I9 which extend over the link switches tothe incoming junctor, the link switches being held as above described byground on conductor 201 which extends to the hold magnets of the linkswitches. Relay 206 connects ground to conductor 2I9 to provide lockingcircuits for relays V200, 208, 2II, 2|2 and A5I3, and both relays 200and 206 provide other holding grounds as will appear hereinafter.

-Upon grounding conductor 5|1, relay 200 also closes a circuit over theinner upper back contact of relay 224, conductor 524, outer upper backcontact of relay 520, conductor 23| to the winding of relay 230 andbattery. Relay 230 signals the centralized sender over the fourconductors which vconnect the terminating sender with the centralizedsender. To do so, it connects polarized relay 225 between the rightwindings of repeating coil 226 which is, in turn, connected byconductors 221 and 228 through cable 229 to repeating coil 9|0 in thecentralized sender. At the same time, relay 230 prepares the fundamentalcircuit for receiving the designation from the centralized sender byconnecting conductor 232 over the inner upper contact of relay 230,inner upper back contact of relay 2-||, conductor 234 to the winding ofrelay 3|0 and battery, which is connected in parallel with batterythrough resistance 3| I and with battery through resistance 309 over theleft back contact of relay 308. Conductor 233 is connected over th-emiddle upper contact of relay 230, outer lower back contact of relay2|I, conductor 235 to the winding of relay 5|4 and ground, relay 5I4being shunted by ground at the inner right back contact of relay 306.The function of the centralized sender in response to this signal willbe described hereinafter.

One of the circuits closed by relay 200 is a locking circuit for selectmagnet 104 and relay 300 which extends over the inner upper and lowerfront contacts of relay 300, conductor 305, back contact of relay 220,conductor 222 to ground at the inner upper front contact of relay 200. Aparallel circuit extends over the middle right back contact of relay306, conductor 3 01, inner upper back contact of relay 520 to conductor222.

When relay 202 was operated as previously deframe vertical on theregister switch over the 4 scribed, it connected the hold magnet 4I0 ofthe `ate with the current which iiows through the two windings in seriesor with the hold magnet kconnected to the two windings. However, thehold magnet 4|0 does operate, vas soon as conductor 22| is grounded,closing-the cross-point 11| prepared by select magnet 104, and locksover its inner upper front contact to grounded conductor 302. Theextension of this locking ground to the windings of relay 220 shunts thelower winding thereof and operates the relay under the in'- iiuence ofits upper winding. The operation of relay 220 opens one branch of thelocking circuit of select magnet 104 and relay 300.

When relay 502 released, a circuit was closed from battery throughresistance 52|, back contact of relay 502, winding of polarized relay522 to conductor 5I'9 leading to the junctor circuit. When relay 200operates, grounded conductor l5|1 is connected over the upper backcontact of relay 523, third lower front contact of relay200, throughresistance 539, back contact of relay 502 to the winding of relay 522 inshunt of battery through resistance 52|. As a result of this connection,a relay in the junctor operates and locks and the locking ground for thejunctor relay, extending back over conductorr5l9, causescurrent to flowthrough relay 522 in the operating direction. Relay 522 in operatingcloses a circuit from grounded conductor 5|1, right contact of relay 522to the winding of relay 523 and battery. Relay 523 operates and locksdirectly to conductor 5| 1. Ihe operation of relay 206 also connectsbattery through resistance 223, outer upper ,backV contact of relay 224,outer lower front contact of relay 206, to conductor 2|6, operating a`relay in the junctor which puts the talking circuit into condition forcommunication between the A and B operators.

The connection of relay 225 across the conductors 221 and 228 closes acircuit in the centralized sender from battery through the lower windingof relay 9I2, outer lower back contact of relay 9| I, lower left windingof repeating coil 9|'9 to conductor 221, through the relay 225 andrepeating coil 226, conductor 228, lower right winding of repeating coil950, inner lower front Contact of relay V9| I, upper winding of relay9|'2 to ground. Relay 9|2 operates and closes an obvious circuit forrelay 9 I3.

The operation of relay 9I3 starts the position nder hunting for an idleoperators position by closing a circuit from battery through the windingof relay 9I4, upper back contact of relays 9I5 .and 9|6, conductor 920to ground at the middle lower front contact of relay 9 I3. Relay 9|4closes a circuit from battery through the lower winding the winding ofrelay 963, back contact of steppingrmagnet 301, inner lower back contactof relay 919, outer front contact of relay 914, lower back contact ofrelay 916, upper outer contact of relay 918, upper normal contacts ofrelay 915 to grounded conductor 929. Relay 998 operates in this circuitand at its left Contact closes a circuit from battery through thewinding of magnet 901 to the operating circuit of relay 906. Magnet 901operates, opening the circuit of relay 999, which releases in turnreleasing magnet 991 to step the brushes of position nder 900. Therelease of magnet 901 recloses the circuit of relay 998 and the samecycle is repeated until an idle position is found.

When a position such as the position of Fig. 6 is occupied, theinsertion of the plugs of the operators headset 605 in the position jack696 closes a circuit from battery through the right winding of relay694, through the plug and jack connection and the transmitter of theheadset to ground through the left winding of relay 694. Relay 694operates, connecting battery over its inner left contact, conductor 612,left normal contacts of key 693, left back contact of relay 602,resistance 601 to conductor 699. As soon as brush 996 encounters theterminal to which conductor 699 is attached, relay 916 operates, openingthe circuit of relay 906 and magnet 901 and bringing the position finderto rest. It is apparent that, if the position nder is resting on an idleposition, relay 916 will immediately operate and the position nder willnot advance.

Relay 916 locks in a circuit from battery on conductor 699, brush 996,inner back contact of relay 916, outer upper contact of relay 911,middle winding and upper front contact of relay 916 to groundedconductor 929. Relay 919 releases relay 914 and when relay 914 closesits back contact, a circuit is completed from battery through thewinding of relay 919, resistance 921, back contact of relay 914, lowerfront contact of relay 916, outer Contact of relay 918, normal contactsof relay 915 to grounded conductor 929. Relay 919 operates, closing acircuit from battery through the winding of relay 915, inner lower frontcontact of relay 919, outer upper back contact of relay 919, uppernormal contacts of relay 915 to grounded conductor 920. Relay 915 locksover its upper alternate contacts to conductor 920 and closes a holdingcircuit for relay 919 under the control of relay 916, In addition, relay919 closes a circuit from battery through the winding and normalcontacts of relay 911, middle lower front contact of relay 919, brush905, conductor 922, left back contact of relay 691 to the winding ofrelay 608 and ground. Relay 911 is marginal and does not operate butrelay 608 operates. Relay 608 closes a circuit from battery over theinner left front contact of relay 604, conductor 612, contact of relay698 through lamp 699 to ground through interrupter 610 to warn theoperator that her position has been seized. Relay 915 closes a circuitfrom battery through the winding of relay 923, lower front contact ofrelay 915, outer upper back contact of relay 1000, outer upper backcontact of relay 911 to ground over conductor 929. Relay 923 connectsthe outer ends of the upper windings of repeating coil 919, over brushes991 and 992, conductors 921 and 928 to the position circuit. The innerend of the upper right winding of coil 910 extends through the upperwindings of polarized relays 924 and 925, inner upper back contact ofrelay 911 to ground over the outer lower back contact of relay 1090 andthrough resistance 1001. 'Ihe inner end of the upper left winding ofcoil 910 extends through the lower windings of relays 924 and 925 tobattery over the outer lower front contact of relay 913 throughresistance 926.

In the position circuit conductor 921 extends through the windings ofrelay 611 to conductor 928. Therefore, relay 611 operates and at itsright contact extends conductor 928 over the outer right back contact ofrelay 613 to the secondary winding of tone coil 614. Conductor 921extends through condenser 615 over the outer left back contact of relay613 to the other side of the secondary winding of tone coil 614. Relay611 at its left contact closes a circuit from battery on conductor 612to the winding of relay 629 and ground. Relay 629 operates and closes acircuit from tone source 616, inner left front contact of relay 629,left back contact of relay 611, right back contact of relay 618, primarywinding of tone coil 614 to ground at the inner right back contact ofrelay 613, thereby transmitting a tone over the conductors 921 and 928,brushes 901 and 902, through repeating coil 910, conductors 221 and 228,through repeating coil 226, contacts of 'relay 266, conductors 214 and215 and thence to the position of the A operator. The operator of Fig. 6may also hear the tone through condensers 620 and 621.

Relay 629 also closes an obvious circuit for relay 691 and completes acircuit for relay 619 which may be traced from battery through thewinding of relay 619, right back contact of relay 611, conductor 622,outer left contact of relay 629, to ground at the outer right frontcontact of relay 604. Relay 601 disconnects conductor 922 from thewinding of relay 698 permitting relay 608 to release and disconnectbattery from lamp 699. With relays 629 and 601 operated, a circuit isclosed from battery through the winding of relay 618, right frontcontact of relay 691,

inner left back contact of relay 613, to grounded conductor 622. Relay61'8 is slow to operate and, after an interval, opens the circuitthrough the primary winding of tone coil 614, thereby interrupting thetone. Relay 618 closes a circuit from battery through the left windingof relay 602, left front contact of relay 618 to ground on conductor622. Relay 692 locks through its right winding and `inner right frontcontact to ground at the outer right contact of relay 629 and extendsits operating ground to the winding of relay 623. In addition, relay 602reconnects lamp 609 over the outer left front contact of relay 692, leftnormal contacts of key 693 to battery on conductor 612. Relay 623operates and recloses the primary circuit of tone coil 614 which nowvextends over the right front contact of relay 618 and the outer leftfront contact of relay 623 instead of over the back contact of relay618. A second tone is therefore transmitted to the A operator. Relay 623also closes a circuit from ground on conductor 622, inner contact ofrelay 623 through the winding of relay 611 and battery. Relay 611 isalso slow to operate and after an interval again opens the primarycircuit of the tone coil to interrupt the second impulse of tone. Inaddition, relay 611 closes a circuit from ground on conductor 622, rightfront contact of relay 611, left back contact of relay 624 to thewinding of relay 613 and battery. Relay 613 operates, locks over itsleft alternate contacts to ground on conductor 622, short-circuitscondensers 620 and 621 and connects ground over its right alternatecontacts to lamp 609 in shunt aasaior of. interrupter 6I0 whereby lamp609 glows steadily to 'inform the operator` that she has been con--nected to the A. operators position.

The A operator then passes the wanted number to the B operatorand the Boperator operates4 the. keys of her key-set to record the number given.Assuming that the called. number isV 3674 the B operator will operatekeys 633, 636, 631 and 634 in succession.

During the transmission4 of the tone and previous to the operation ofthe key-set, the sender and the key pulsing circuits are prepared foroperation. by the establishment of three registering circuits. Theoperation of relay 602, as previously described, disconnects batteryfrom conductor 609- thereby releasing relay 9-I6 which in turn releasesrelay 9I9. With relay 9I9 released, the first registering conductor 922is disconnected from relay 91.1 and connected over the middle backcontact of relay 9I9, outer right front contact oi relay 923,. conductor929, winding of relay H03, normalcontact of relay .IIOI, right windingof relay I |02, lower normal contacts of relay H35, upper winding oiunits register relay H43, lower winding of units registery relay IIj42to ground. The release of relay 9-I9 also extends the second registeringconductor 930 from brush 904, middle right contact of relay 923, outerback contact of relay 9IY9, conductor 932 through the winding of relayH00 and thence to vground as traced from the winding of relay II03. Thethird registering conductor 93I' extends from brush 903, inner rightfront contact'of relay 923, conductor 933, through the left winding ofrelay H02 but the circuit` is incomplete'at this time.

In the position circuit, conductor 922 extends over the left frontcontact of relay 601, conductor 56|.; through resistances 62'5Y and 626,inner left contact `of relay 621,l conductor 628, left front contact' ofrelay 6'II to battery onconductor 612, While conductorY 930 extends overthe outer right front Contact of relay 602, conductor 652, throughresistances 649 and 650, outer left contact of relay 621 to battery overconductor 628 as traced. Conductor 93|Y extends through the winding ofrelay 64I, leftYback contact of relay 642, right backl contact of relay-643 to ground over key 644.

Relay H00 and. H03, as Well as relay H02 and the units-register relays,operate the circuits above traced'. Relays H00and H03 close. a circuitfrom ground atthe inner upper front contactof relay- 9513, conductor934, front contact ofrelay- I'Illil-iront contactof relay H03, throughthe lower lwinding of relay I IOI and battery.

Relay HI operates in this circuit, opening the circuit of relay H02 andthe register relays which release. It also` closes a holding circuit foritself'from battery in the position circuit, through the windings ofrelays H00 and H03. as tracedyalternate contacts and upper winding ofrelay Htl-I, vconductor 935 to ground at the second upperiront contactof relay 903. Relay H-`0I also closes; 'a circuit 'from ground onconductor 934, upper front contact vofr relay IIOI, windings of relaysIjlilV and HI5 to battery` Relays IH5 and H-I' operate, relays HI'Bclosing at its left Contact a 'locking' circuit for the two relays toground onV conductor 934. At its right contact rel-ay H49 also closes acircuit from grounded conductor-'934 to the windings of relays H26 andi'I25a/nd battery.` Relays H25 and H26 operate, relay'll26 closing alocking circuit for itself and an operating circuit for relays H36 andH35. Relay H36 locks vrelays H35 and H36 to conductor 934' andy operatesrelay H46` through resistance H41., kRelay H49. lalsolocks to`conductor934..

With relay H35 operated, a circuit isclosed from battery throughresistance H48, upper back.A

contact of 'relay H45 through the upper winding of relay IH4,upperalternate contacts of relays HI5, H25 and'jH35,.lef t winding ofrelay H02.,

to' conductor 933, completing the third registering circuit which was.previously traced. to conductor 9,33v and operatingjrelay 64Iy inthe'posi'- tion circuit. Relays 64I and. H02 operate in this. circuitbut relay H02 is. ineiective at this time, Relay 64I closes a lockingcircuit for itself over itsouter left contact to ground on conductor 622Y and extends this ground over its inner left contact to the winding,"of relay 642 and battery on conductor 629.v Relay 642 locks over its letfront contact and right back contact of relayV 643 to ground on key644,"opens the operating circuit for relay. 64Iv and closes a circuitfrom batteryv through Vthe lwinding. of relay 621,. inner right of relayHOI connects ground fromconductor 934 over the inner upper backcontactoirelay I IOI to conductor I I50,.there by completing a cir-Y cuit oyerthe right front contact of relay H46 to the winding of relay H45 andbattery. Relay H45 locks to conductor H50, disconnects battery fromconductor 933 and extends that conchlctorv to4 ground-at, the .outerupper backl contact of. relay II0I.`

The operation Qf-re'lay H45 releases relay 94| :whieh new extends,conductor 93| through .me

l key 633, batteryis connected from conductor. 62.8

over thelowercontact of key 633 through low resistance ,9.495 toconductor 96,2 and over'the upper Contact oikey 633 throughv lowresistance 646 to conductor 663. Conductors 662 and 663 extend. aspreviously traced to conductors 932 and 933, respectively. Conductor932Y extends through the winding, of relay H00, normal contacts ofrelayv Hill, right winding of relay H02, lower. alternate contacts ofrelays H35, H25 and HI5, upper windingof relay I I I3, lower winding ofrelay-I I I2 to; ground, while conductor, 933 ex-` tends throughthe leftwinding of relay I I02, up. per alternate contacts of, relays` H35, IIE5 and I H5, upper winding of relay IH4, outer upper front contact ofrelay I |45, to ground at the cuter upper back ycontact of relay H0 I.vRelays H00 and H02` operate.` Since onlylow resistance649 was includedin thecircut over conductor .932, marginal`relay`HI3 operates in thatcircuit as well Aas relay H,I.2, and -since only low resistance 646 was.included in the circuit over conductor 933, relayl I I4'operates.. Theoperation of relay H35 and H25, inner lower front contact of relay III5,winding of relay HII and battery. Relays HH, |II2, |II3 and H|4 lock toconductor H50. Relays HH and H|2 close obvious circuits for relays HI8and IHS.

The operation of relay H02 closes a circuit from grounded conductor H50,front contact of relay H 02, outer lower front contacts of relays H35and H25, inner upper front contact and winding of relay III5 to battery.This circuit is in shunt of relay ||I6 and causes that relay to releasebut holds relay I H5 operated until the key is released at the key-set,when relay III5 also releases transferring the registering circuits tothe hundreds register I |20.

The operation of key 636 to record the hundreds digit connects batterythrough resistance 625 to conductor 66| and battery through resistances641 and B46 to conductor B03. Conductor 66| extends as previously tracedto conductor 929, through the winding of relay H03, normal contacts ofrelay HOI, right winding of relay H02, lower alternate contacts ofrelays H35 and H25, lower normal contacts of relay |H5, upper winding ofrelay H23, lower winding of relay H22 to ground. Since only a lowresistance is included in this circuit, relays H22 and I |23 bothoperate, locking to conductor I |50. Conductor E33 extends as previouslytraced to the upper alternate contacts of relay H25 and over the uppernormal contacts of relay III5 to the lower winding of relay H24 andground. Since high resistance 641 was included in this circuit, relayH24 does not operate. Relay H02 in operating closes a circuit fromground on conductor H50, front contact of relay H02, outer lower frontcontacts of relays H35 and H25, inner upper back contact of relay II I5,to the winding of relay H25 and battery. Relay H26 is shunted by thiscircuit and releases, relay H25 being held operated until the key isreleased at the key-set when relay H25 also releases, transferring theregistering circuits to the tens register H30.

The operation of key 63T for the tens digit connects high resistancebattery to both conductors and 663, resulting in the operation of relaysH03, H02 and H32 in a manner similar to that described for previousregistrations. Register relay H32 locks to grounded conductor H50. RelayH02 now shunts relay H36 and holds relay |I35 which releases when thekey is released, to transfer the registration circuits to the unitsregister H40.

The operation of key 634 to record the units digit connects lowresistance battery to conductor 663 and high resistance battery toconductor 652 thereby operating relays H00, H02, H44, H42 and H4I. Theoperation of relay H02 completes a circuit from grounded conductor H50,front contact of relay H02 over the` lower back contact of relay |35, tobattery through resistance I |41 thereby releasing relayV H46. Withrelay H46 released, as soon as relay H02 closes its back contact at theend of the pulse, a circuit is closed from grounded conductor I |50,back contact of relay H02, outer lowerl front contact of relay H45,right back contact of relay Hll, conductor |I|, upper back contact ofrelay |003 through the winding of relay |000 and battery. Relay |000locks over its outer upper front contact to grounded conductor 034 andVprepares for the transfer of the designation from the centralized senderto the terminating sender. Relay |000 operated, disconnects ground fromthe windings of relays 024 and 925 thereby opening the circuit of relayBH which releases, disconnecting battery from conductor 028 andreleasing relays 642 and 029. With relay 620 released relays 601 and 602also release and ground is disconnected from conductor 622 therebyreleasing relay 6|3. The release of relay 602 restores the connection ofbattery through resistance 00| to conductor 600 thereby placing theposition circuit in condition to be selected in connection with anothercall, In addition, relay |000 opens the circuit of relay 923disconnecting the position nder from the centralized sender circuits.

Relay |000 in operating also disconnects the conductors 232 and 233 fromthe winding of relay |002 and completes the fundamental circuit fortransferring the designation to the terminating sender. This circuit wasprepared when relay 9|3 operated by the operation of relays |005 and|005. Relay |005 operates in a circuit from battery through its winding,back contact of relay |0|5, outer upper back contact of relay |020,conductor 036 to ground at the inner lower front contact of relay 9|3.With relay |005 operated, the circuit of relay |006 extends from batterythrough the winding of that relay, lower front contact of relay |005,inner upper back contact of relay |028 to ground over conductor 036.Relay |000 locks over the inner upper back contact of relay |028 togrounded conductor 936 independent of relay |005. Therefore, when relay|000 operates, a circuit is closed in the centralized sender fromconductor 232, lower front contact of relay |000, lower back contact ofrelay |003, back contact of relay |021, lower back contact of relay|028, outer upper front contact of relay |000, Winding of stepping relay|004, inner upper back contact of relay |003, inner upper front contactof relay |000 to conductor 233.

The closure of the fundamental circuit in the centralized sender causesthe operation of relay 3I0 in the terminating sender. Relay 3|0 closes acircuitA from batteryithrough thc winding of relay 308, middle upperfront contact of relay 300, which has been held operated following theregistration of the frame designation, outer right back contact of relay306 to ground at the front contact of relay 3|0. Relay 308 locks to thefront contact of relay 3|0 independent of relay 300 and closes anobvious circuit for relay 306 which locks to ground over the outer lowerfront contact of relay 300. 'I'he operation of relay 306 opens thesecond locking circuit for relay 300 and that relay releases, leavingrelay 306 dependent upon relays 308 and 3|0.

With relays 306 and 308 operated, ground is disconnected from conductor235 permitting the `steppingrelay 5I4 to operate. Relay l5|4 closes acircuit from ground over the outer upper front contact of relay 5|3,front contact of relay 5|4, lower front contact of relay 5I3 to thewinding of relay 530 and battery. Relay 530 closes a circuit from groundover its lower contact, normal contacts of jack 53|, conductor 532, leftback contact of relay 3|2, winding of relay 3|3 to battery. Relay 3|3closes a holding circuit from battery through its winding, right windingof relay 3|2, back contact of relay 3|4, left contact of relay 3I3 toground at the outer right front contact of relay 308, but relay 3|2 doesnot operate, being shunted by the operating circuit of relay 3|3.

Relay 530 at its upper front contact connects ground to conductor 234thereby holding relay At the terminating sender the operation of relays308 and 300 connects ground to the right armatures of relay 3|2. Whenrelay 530 releases after the rst revertive pulse, relay 3`|2 operates inthe holding circuit of relay 3|-3 and closes a circuit from ground atthe inner left front contact of'relay 308, right front contact of relay312,l left back contact of relays 324 and 322, right back contacts ofrelays 323 and 325 to the winding of relay 32| and battery. Relay 32|operates and locks over its inner right front contact, normal contactsof relays 322, 323, 324 and 325, outer right front Contact of relay 305to ground over conductor 301. A parallel locking circuit extends fromthe contact of relay 325 over the up'-v per normal contacts of relay 300to groundedy conductor 22|. The next operation of relay 530', groundingconductor 532 closes a circuit over the left front contact and leftwinding of relay 3|2 through the right winding of relay 3M and loat- Itery. Relay 3|4 opens the operating circuit of relay 3|3 and that relayreleases. When relay 530 releases, relays 3M and 3|2 also release. Acircuit is then closed from ground over the right back contact of relay3|2, inner left front Contact of relay 32| to the winding of relay 322andbattery. Relay 322 locks over the chain circuit previously traced,opening the locking circuit for relay 32| which releases. Subsequentoperations of relay 530 cause relays 3|3, 3M and 312 to operate as abovedescribed so that for each odd pulse ground is closed to the countingrelays'over the front contact of relay 3|2 and. for each even pulseground is connected to the countingV relays over the backrcontact ofrelay 3|2. The third, fourth, fifth and sixth' pulses operate relaysV323, 324, 325 and 323, respectively. Relay 325 locks over the backcontact of relay 32|, therefore remaining operated when relay 32S isoperated. Relay 326 locks through its right winding and inner rightfront contact over the outer right front contact of relay 300 toconductor 301 independent of the other counting relays and thereforere-f maining operated during any subsequent pulses. The seventh, eighth,ninth and tenth pulses operate relays 32 322,l 323 and 320,respectively, relay 32| releasing relay 325.

The regular terminating sender is arranged to receive the wanted numberfrom the originating sender in the forro of three selections known asincoming brush, incoming group and nal brush selections, which aretranslated from the thousands and hundreds digits of the Wanted number,followed by nal tens and final units selections corresponding directlyto the tens and units digits of the wanted number. Therefore, in orderto provide for theY simple modification of terminating sendersv to workwith a centralizedY B operators equipment or vice versa, the terminatingend of the present sender is likewise equipped with a cross-bar registerhaving ve verticals for receiving five selections and translating theminto a numerical de's'igriationv for transmission to the marker.

In the centralized end 'of the sender theV five selections varecontrolled by the steering relays |030 to |039. When relay 553' operatedgrounding conductor 834, a circuit was closed over the middle upper backcontact of relay|000 through the windings of relays |030l and |03 inseriesI to battery, relay |030 closing a locking circuit through thewindings of; relays w30-and |03|-, front contact of relay |030, upperback contact of relay |033' to grounded. conductor 034, independent ofrelay |000.

Withv relays |030 and |03| operated, vthe operation of relay |004, bythe establishment of the fundamental circuit, closes a circuit fromground over thev upper back contactof relay |001, front contactofrrela-y |004, lower back contact of relay |001, back contacts ofrelays |020v and |02|, inner upper front contact of relay |03|,conductor |000,` middle' upper front contact of relay |||4, outer upperfront contact of relay |||3, lower front contacts of relays |9 and |||B,conductor H52, upper front contact of relay |005, winding of relay |0|lto' battery. Relay |0|| locks through thewnding of relay |02| to' groundat the lowermost contact of rel-ay |006, but relay |02 does not operate,being shunted by the opera ating circuit for relay |0| t. When relay 530operates, shuntingthe stepping relays of the two senders, relay |0013releases, permitting relay |024. to operate. When relay 530' releasespermitting relay |004 to reoperate, the counting relay circuit extends,as above tra-ced, tothe upper armature of relay |02| and` thence overthefront contact of relay |02 upper back contacts of relays |030, |035and |032 to the winding of relay |0'|0 and battery. RelayV |0|0operates, lock-ing through the windings of rel-aysl02-1 and |020 inparallelto ground at the outer lower front con'- tact of relay |000.When relay |000 is-shunted andA releases for thesecond time, relays |021and |020 operatev in this locking ci-rcuit.- The operation of relay |021opens the fundamental circuit, releasingrrelays 3|0, 5M and |004, andbringing the lselection to an end.

Relay |020 closes a circuit from ground atl its contact over thelowerlcack contacts of lrelays |030, |031, |035 and |033, lower frontcontactfof relay |03| to the ywinding ol relay |032 and battery; a Relay|032v closes ai locking circuit for i-tself through the winding of relay|033-, outer lower front contact of relay|032,rupper back contact ofrelay |035 to grounded conductor 9734-. RelayY |032 also closes acircuitfrom grounded conductor 934, outer upper front contacter" relay |03|,inner lower contact of relay |032 to the winding. of relay |028 andbattery. Relay |028 further opens the fundamental circuit anddisconnects grounded conductor 030 from the oping that relay toreleaseand open the fundamental.A circuit at an additional point.A YRelay |028alsoopens theoperating circuit of relay |005 and that relay releases.The release of relay |000 opens the locking circuit of lthe countingrelays and these relays release. The release of relay |020' permitsrelay |033 to operate in the locking circuit of relay |032 and openthelocking circuit of relays |030 and |03| so that these relays release.The releaseY of relay |03| opens the cir- Vcuit of relay |020 and thatrelay releases, restering the circuits of relays |005 andV |000'whichnow reoperate. Withl relay |006 reop'erated-` the fundamental circuit isreclosed and the Centralized4 sender is' ready to transmit the nextselection..

At the terminating sender the two revertive pulses which satisfy thecentralized sender cause the ope-ration of relays 32| and 322 leavingrelay 322 operated` and locked when the fundamental circuit was opened.The release of relay 3|0 in turn releases relays 308 and 303. With relay306 released, a circuit is closed from ground at the lower back contactof relay 534, conductor 535, lower normal contacts of relay 300, rightback contact of relay 320, first left back contact of relay 306, outerleft front contact of relay 322, conductor 33|, winding of select magnet10|, winding of relay 130 and battery. Magnet 10| prepares thecrosspoints at the No. l level of the register switch and extends itsoperating ground to the winding of relay A300 as previously described.Relay 300 locks over the back contacts of relays 220 aind 306 as before,thereby also locking the select magnet 10|. At its outer upper frontcontact relay 300 connects ground on conductor 302 over the upper frontcontact of relay 204 to resistance 203 and battery in shunt of thewinding of relay 202 which thereupon releases. Relay 204 is heldoperated over the normal contact of relay 202 after that relay releases.With relay 202 released and relay 204 operated, the windings of relay220 are connected over the lower front contact of relay 204, lower backcontact of relay 202, conductor 230, outer upper contact of hold magnet4|0, upper back contact of hold magnet 4|2, to the winding of magnet 4||and battery. Magnet 4|| closes cross-point 112 and locks over its innerupper front contact, conductor 42|, through cable 422 to ground at thefourth upper front contact of relay 206. The closure of this lockingcircuit extends ground back to the upper winding of relay 220 causingthat relay to operate opening one locking circuit for relay 300.

When the fundamental circuit is reclosed at the centralized oice, relays3|0, 308 and 306 reoperate and relay 300 releases, in turn releasingrelay 204. The remaining selections are performed in essentially thesame manner, relay 300 operating relays 202 and 204 on alternateselections and releasing them on the following selections.

Since the thousands and hundreds digits have been translated intoincoming brush, incoming group and final brush selections, with relays|032 and |033 operated to control incoming group selection, the countingrelay circuit extends as previously traced to the armature of relay|02|, over the back contact of that relay, inner upper front contact ofrelay |033, conductor |040, inner upper front contact of relay |||3,inner upper front contact of relay i I4, lower back contact of relayH24, back contact of relay |023, winding of relay |0|3 and battery. Forthis selection, when relays |0|| and |02| are operated, after threerevertive pulses the counting relay circuit extends over the frontcontact of relay |02|, upper back contacts of relay |038 and |036, upperfront Contact of relay |032, lower back Contact of relay 940, winding ofrelay |0|0 to battery. At the end of the selection, the fundamentalcircuit is broken as above, resulting in the operation of steeringrelays |035 and |034 and the release of relays |032 and |033. In theterminating sender the four revertive pulses leave relay 324 operated,resulting in the operation of select magnet 103 and hold magnet 4|2,closing crosspoint 113.

With relays |034 and |035 operated, the selection is controlled by thehundreds register alone and the counting relay circuit may be tracedover the back contact of relay |02| over the inner upper front contactof relay |035, upper front cont-act of relay |23, outer upper frontContact of relay H22, upper back contact of relay ||2|, conductor H52,upper front contact of relay |005, winding of relay |0|| and battery.Two pulses satisfy the centralized sender resulting in the closure ofcross-point 114 at the terminating sender.

The nal tens selection takes place with relays |036 and |031 operated.In this case, the counting relay circuit extends as traced to the backcontact of relay |02|, inner upper front contact of relay |031, backcontact of relay H33, lower front contact of relay |32, lower backcontact of relay ||3|, back contact of relay |022 to the winding ofrelay |0|2 and battery. The first two pulses permit relays |022 and |02|to operate, whereupon the counting relay circuit is transferred over thefront contact of relay |02|, upper back contact of relay |038, outerupper front contact of relay |036, upper back contact of relay ||34 tothe winding of relay |0|6 and battery. The third pulse permits relay|020 to operate, which transfers the counting relay circuit to theWinding of relay |0|5 which operates when the stepping relay reoperates.Relay |0|5 in operating releases relay |005. As a result of the fourth,fifth, sixth land seventh pulses, relays |025, |024, |023 and |022operate. With relay |022 operated, the counting relay circuit isextended over the front contact of relay |022, back contact of relay|005 to the winding of relay |0|0 so that eight pulses satisfy thesender. As outlined previously, eight revertive pulses operate relays32| to 326, leaving relay 326 operated, followed by relays 32| and 322,relay 322 remaining operated at the end of the eighth pulse. Therefore,when relay 306 releases following the opening of the fundamentalcircuit, the select magnet circuit extends from grounded conductor 535,lower normal contacts of relay 300, outer right front contact of relay326, outer left back contact of relay 300, inner right front contact ofrelay 322, conductor 332, winding of select magnet 401 and battery. Withselect magnet 401 operated, the operation of hold magnet 4|4 closescross-point 415.

The nal units selection takes place in a manner similar tc theselections above described and results in the closure of cross-point116. After final units selection has been transmitted relays |0|0, |020and |021 are operated as above, opening the fundamental circuit. Sinceno circuit exists for relay |028, there is no means for reclosing thefundamental circuit and it remains open until the centralized sender isreleased.

In the terminating sender when hold magnet 4|5 operates after theregistration of the final units selection, ground is connected toconductor 235 in shunt 0f the winding of stepping relay 5|4 Ato preventany false pulses by that relay. Magnet 4|5 also closes a circuit fromground over its inner lower front contact, conductor 424, winding ofrelay 520 and battery. Relay 520 opens the circuit of relay 230 whichopens the fourconductors leading to the centralized sender. Opening theconnections between conductors 221 and 228 releases relay 9|2 which inturn releases relay 9| 3 removing the locking grounds from the variouscircuits and restoring the centralized sender to normal.

Relay 520 also opens the locking circuit for relay 300 previouslycontrolled by relay 306 permitting relay 300 to release, in turnreleasing relay 204. In addition, relay 520 closes a circuit frombattery over the lower normal contacts of relay 5|6, upper normalcontacts of relay 5|5, outer lower front contact of relay 523, frontcontact of relay 520, outer upper front contact of relay 200, toconductor 24| which extends through cable 536 to the marker connector800 indicated at the left of Fig. 8. When the connector is operated thecross-bar register is connected to the ,marker and the recorded numbertransmitted thereto, the register translating the selections back into anumericaldesignation. u

.With cross-points 112, 113, 114, 415, 116 and 11| closed, theyfollowing conductors are grounded directly by cross-pointsv which aresupplied with groundover conductor 423 and the back contact ofrelay1,62; thousands conductors1l2, 1| I; hundreds conductors 12|,v 122; tensconductors 132 and 134; units conductor 143 and frame conductor 153. v vFrame tens conductor 164 is grounded over the upper front contact ofrelay 30|.

The marker connects ground through the marker connector 800 toconductors 30|, 802, 803 and V801i. It will be observed that ground overone of these conductors is connected by the crosspointsV to each of theconductors which donot receive ground over conductor 423. For example,thousands conductors 1|| and 1|2 are grounded by cross-points 113 and112, respectively. The remaining thousands conductors 1|3 and 1|4 aregrounded by cross-point 112 from ground supplied Iover conductor 803.The cilice identication conductor 2.50 isgrounded over the lower frontcontact of relay 208 and conductor 802. Reorder conductor 544 isgrounded over the upper baclrv contact of relay 534 and conductor 802.

Therefore ground is connected either directly or indirectly to all ofthe registering conductors connecting the sender with the marker. As aresult, all of the register relays in the marker are operated to close achain circuit (not shown) as a check for faults in theV connectionsbetween the sender and marker. If the chain circuit is closed, ground isremoved from conductors 80| to` 034' and the registration remaining inthe marker is used to select, test and establish a connection with thewanted line. During these operations themarlier is vconnected directlywith the incoming junctor under the'control of a circuit completed overconductor 2 |1. d

In the selection of the wanted line the marker combines the thousandsand hundreds registrations-to operate a relay representing a block offive hundred numbers. Anurnber of such relays are indicated byrelays 8|0to 8|3. Where the incoming junctor serves more than one oiice thesenumbers may occur in either ofce and the marker rnust discriminatebetween the oiices. With conductor 250 grounded over conductor 802,

relay 305 is released following the establishment' of the chain circuitand operates relay 806 over itsback contact. With relay 806 operated,the circuit of the 50B-block relay closed by the thousands and hundredsregisters represented by relays 301 and 803, respectively, extends overfront contactsv of relay 806 to relays 8|0 and 0H which arerindividualto the A office.

W'hen the marker has completed its function, it connects ground toconductor 531 closing a circuit over the lower back contact of relay 538to the winding of release relay |6 and battery. Relay 5|6 disconnectsbattery from the marker connector 800 thereby releasing both theconnector and the marker. In addition, relay 5|6 locks over its Icuterupper and lower front contacts to grounded conductor 5 l1 under thecontrol of relay 200 and connects ground to conductor 2|8 to hold thesender busyy until released. The operation of relay 5|6 disconnectsground from conductor 2|3 and the locking circuit 'of relay 206 butthat-relay, aswell as the hold magnets of the link switches, remainsoperated untilV ground is removed from conductor 2|3 by the markerconnector. When this occurs relay 20S and the link switches release,followed by relay 200.l WithirelaysZ and 200 released the holdingcircuits for the various relays of the sender are opened andthe senderis restored to normal.

CaliA over a innetor terminating at oice B in the'operation of relay 800and the extensionv of the operating. circuit orthe 500-block'relays torelays 8|2 and ljindividual to the B office.

Call over a y'unctor terminating at both office A Assuming that the.connection has beenextended over incoming junctor v|34 belonging to thegroup of junctors which have access to more than one office, relay H9will be operated, in turn operating group relay |20 If the same group ofsenders is seized, sender grouprelay H4 will also be operated. .Theoperation of relay |23 connects ground to conductor H5 over` the contactof relay ||4 to conductor 12|. When the sender is seized and relay 500operated, this ground isextended over the fourth lower front contact ofrelay 500 to conductor 540, 4winding of relay 2i! and*` battery. .Relay2|| locks to conductor ZIB when relay 236 operatesA The operatingcircuit of relay 200 which extends as previously traced to the upperback contact of relay 252 now in completed over the upper back contactof relay 2|2,. outer upper front contact of relayp2il, upper backcontact of relay 208, second lower front contact ofrelay236 to conductor2|0. y

When relayl 230 operates, connecting the ter-A minating sender 'with the.centralized sender, conductor 232 is connected over the inner upperfront contact of relay230, inner lower frontl contact of relay 2| y|,conductor 235 to the winding of relay 5| 4 and ground, while conductorl233 is connected yover the middle upper front contact of relayA 230,middle upper front contact of relay 2| |,'conductcr 234to Ithe windingof relay 3|0 and battery.V Battery and ground are, there-f fore,reversed on the fundamental circuit connecting the two senders. In Vthecentralized sender the current liowing through the winding of polarizedrelay |002 is in a direction to operate that relay which in turnoperates relay |003. Relay |003 locks over its inner upper front contactto grounded conductor 936., Relay |003 reverses the direction oflcurrent flow through the stepping relay |004 to compensate for thereversal at the terminating sender. During the interval between theoperation of relay 923 and the release of relay S50, relay 003 alsoconnects ground over its outer lower front contact, outer lower frontcontact of relay 9!9,middle right iront contact of relay 323, brush 904,conductor 930, right back contact of relay B02 to the left winding cfrelay B24 and battery. Relay 624 locks in. a circuit from batterythrough its right -wind-

